IGF is a factor which takes a very important role in controlling proliferation, differentiation and cell death (apoptosis) of epithelial cells of the breast, prostate, lung, colon and the like organs, and its action is carried out via an IGF receptor (hereinafter referred to as IGF-IR) existing on the cell surface (Endocrine Reviews, 16, 3-34, 1995). Also, it is known that a protein called IGF-binding protein (hereinafter referred to as IGFBP) is existing and regulating the activity of IGF promotively or inhibitively (Endocrine Reviews, 16, 3-34, 1995).
As the IGF, two types of IGF-I and IGF-II exist, and each of them comprises a single chain polypeptide and has about 40% homology with an insulin precursor proinsulin at the amino acid level (Advances in Cancer Research, 68, 183-223, 1996). As the IGF-R three types of insulin receptor exist, IGF-I receptor (hereinafter referred to as IGF-IR) and IGF-II receptor (hereinafter referred to as IGF-IIR). Each of the insulin receptor and IGF-IR belongs to the tyrosine kinase type receptor family and exists on the cell membrane as an α2β2 hetero tetramer, after forming S—S bond of a 135 kDa α subunit and 95 kDa of β subunit formed from a single chain precursor as a result of its digestion with a protease (Endocrine Reviews, 16, 143-163, 1995, Breast Cancer Research & Treatment, 47, 235-253, 1998). The insulin receptor and IGF-IR have about 60% homology, and insulin and IGF-IR, and IGF and insulin receptor, binds to each other though weak and act (Journal of Biological Chemistry, 263, 11486-11492, 1988, Journal of Biological Chemistry, 268, 7393-7400, 1993). The existstance of a hybrid receptor comprising the αβ subunit of insulin receptor and the αβ subunit of IGF-IR has been proved, and it is considered that the hybrid receptor has high binding affinity for IGF-I than for insulin and acts as IGF-IR, but its role in intravital is unclear (Endocrine Reviews, 16, 3-34, 1995, Endocrine Reviews, 16, 143-163, 1995). The IGF-IIR has a single chain structure, and there are three ligand-binding regions in its extracellular region. One of the ligand-binding regions is an IGF-II-binding region, and the other two are regions which bind to mannose-6-phosphate-containing proteins [renin, proliferin, thyroglobulin, endogenous transforming growth factor-β (TGF-β) and the like] (Endocrine Reviews, 16, 3-34, 1995). It has been reported that the endogenous TGF-β is activated by its binding to IGF-IIR (Breast Cancer Research & Treatment, 52, 175-184, 1998, Hormone & Metabolic Research, 31, 242-246, 1999). The IGF-IIR does not have tyrosine kinase activity and binds to only IGF-II among IGF. Since IGF-II is degraded by its binding to IGF-IIR, it is considered that IGF-IIR acts as an antagonist of IGF-II (Breast Cancer Research & Treatment, 52, 175-184, 1998).
Ten types of IGFBP (IGFBP-1 to IGFBP-10) have so far been known, and six types among them (IGFBP-1 to IGFBP-6) have high binding affinity for IGF (Proceeding of the National Academy of Sciences of the United States of America, 94, 12981-12986, 1997). IGFBP-1 to IGFBP-6 have a high homology of 40 to 60% at the amino acid level. It has been revealed that IGFBP regulates the function of IGF by undergoing various post-translation modifications such as degradation and phosphorylation and thereby exerting influences upon the transfer of IGF, inhibition of degradation and binding to receptor (International Journal of Biochemistry & Cell Biology, 28, 619-637, 1996, Endocrine Reviews, 18, 801-831, 1997). IGFBP-1, IGFBP-2, IGFBP-3 and IGFBP-5 have a case of promoting the action of IGF and a case of inhibiting the same, and the actions of IGFBP-2, IGFBP-3 and IGFBP-5 upon IGF are regulated by the degradation of IGFBP, and the action of IGFBP-1 by the phosphorylation of IGFBP-1, respectively (Endocrine Reviews, 16, 3-34, 1995, International Journal of Biochemistry & Cell Biology, 28, 619-637, 1996, Endocrinology & Metabolism Clinics of North America, 25,591-614, 1996). In addition, the binding affinity of IGFBP-1, IGFBP-2, IGFBP-3 and IGFBP-5 for IGF is reduced when they bind to a specific receptor existing on the cell membrane. As a result, IGFBP and IGF are dissociated to form free IGF (Endocrine Reviews, 16, 3-34, 1995, International Journal of Biochemistry & Cell Biology, 28, 619-637, 1996, Endocrinology & Metabolism Clinics of North America, 25, 591-614, 1996). On the other hand, IGFBP-4 and IGFBP-6 have the activity to inhibit the action of IGF (Endocrine Reviews, 16, 3-34, 1995, Endocrinology & Metabolism Clinics of North America, 25, 591-614, 1996). In intravital, 90% or more of the blood IGF binds to IGFBP-3 and an acid-labile subunit, and exists in the form of a high molecular weight complex of about 150 kDa, thereby inhibiting degradation of IGF and its drain into the extra vascular region (Journal of Biological Chemistry, 264, 11843-11848, 1989).
Both of the IGF-I and IGF-II show strong promoting proliferation activity to a large number of cancer cells (sarcoma, leukemia, prostate cancer, breast cancer, lung cancer, colon cancer, gastric cancer, esophageal cancer, hepatic cancer, pancreatic cancer, renal carcinoma, thyroid gland cancer, brain tumor, ovarian cancer, uterine cancer) (British Journal of Cancer 65, 311-320, 1992, Anticancer Research, 11, 1591-1595, 1991, Annals of Internal Medicine, 122, 54-59, 1995, Oncology, 54, 502-507, 1997, Endocrinology, 137, 1764-1774, 1996, European Journal of Haematology, 62, 191-198, 1999), and over-expression of IGF has been identified in a large number of cancer cells (British Journal of Cancer, 65,311-320, 1992). Also, it has been reported that expression amounts of IGF-II and IGF-IR are more those in higher metastatic cancer cells than those in lower metastatic cancer cells (International Journal of Cancer, 65, 812-820, 1996). It has been revealed that such functions of IGF occur mainly via IGF-IR (Endocrinology 136, 4298-4303, 1995, Oncogene, 28, 6071-6077, 1999), but IGF-II also acts via the insulin receptor in breast cancer cells (Oncogene 18, 2471-2479, 1999).
It has been reported that, in the case of transgenic mice which over-express IGF-I in prostate epithelial cells, about 50% of them develop prostate cancer after about 6 months (Proceedings of the National Academy of Science of the United States of America, 97, 3455-3460, 2000). Also, it has been shown that expression of IGF-I and IGF-IR is increased by the acquirement of androgen-independent proliferation ability in a human prostate cancer cell transplantation model mice (Cancer Research, 61, 6276-6280, 2001).
IGF is also concerned in the proliferation of cancer cells by mutually reacting with other factors. It has been reported that the activity of IGF-I is increased and expression of IGF-I and IGF-IR is induced by estrogen in breast cancer cells (Endocrinology, 136, 1296-1302, 1995, Journal of Biological Chemistry, 265, 21172-21178, 1990, Journal of Steroid Biochemistry & Molecular Biology, 41, 537-540, 1992, British Journal of Cancer, 75, 251-257, 1997). In addition, it is known that estrogen inhibits production of IGFBP, reduces expression of IGF-IIR, and increases expression of IGFBP degrading enzyme in breast cancer cells (Biochemical & Biophysical Research Communications, 193, 467-473, 1993, Molecular Endocrinology, 5, 815-822, 1991).
On the contrary, it has also been reported that IGF-I increases expression of estrogen receptor (Endocrinology, 127, 2679-2686, 1990, Journal of Cellular Biochemistry, 52, 196-205, 1993), and that IGF-I and IGF-II increase the activity of estrone sulfatase which hydrolyses estrone sulfate into estrone, in breast cancer cells (International Journal of Molecular Medicine, 4, 175-178, 1999).
In addition, IGF cooperatively acts with an epithelial cell growth factor (epidermal growth factor; hereinafter referred to as EGF). In cervical cancer cells, EGF increases expression of IGF-II, and IGF increases the growth activity of EGF (Proceedings of the National Academy of Sciences of the United States of America, 92, 11970-11974, 1995, Cancer Research, 2, 56, 1761-1765, 1996). It is also known that EGF increases the amount of free IGF by inhibiting expression of IGFBP-3 and thereby has a synergistic effect on cell growth activity (Cancer Research, 54, 3160-3166, 1994).
It is known that the function of several factors having anti-cell proliferation activity is exerted by inhibition of the IGF promoting activity to proliferation. The function of TGF-β and retinoic acid to inhibit proliferation of breast cancer cells is exerted by the inhibition of the IGF function as a result of the induction of IGFBP-3 expression (Journal of Biological Chemistry, 270, 13589-13592, 1995, Cancer Research, 56, 1545-1550, 1996, Endocrinology, 136, 1219-1226, 1995). In addition, vitamin D and its synthetic derivatives inhibit the function of IGF to promote proliferation of beast cancer cells and prostate cancer cells, and the action is based on the increase of IGFBP expression and inhibition of IGF-IR and IGF-II expression (Journal of the National Cancer Institute, 89, 652-656, 1997, Journal of Molecular Endocrinology, 20, 157-162, 1998, Journal of Endocrinology, 154, 495-504, 1997, International Journal of Oncology, 13, 137-143, 1998).
It has been reported that tumor suppressor gene products also have influence upon the function of IGF. For example, in sarcoma cells and the like, the wild type p53 protein induces IGFBP-3 expression and inhibits IGF-II and IGF-IR expression (Nature, 377, 646-649, 1995, Cancer Research, 56, 1367-1373, 1996, DNA & Cell Biology, 17, 125-131, 1998, Proceedings of the National Academy of Sciences of the United States of America, 93, 8318-8323, 1996, Endocrinology, 139, 1101-1107, 1998). In breast cancer cells, on the contrary, it is known that the p53 protein is phosphorylated by the function of IGF-I and is transported from the nucleus into cytoplasm, thereby losing the function of p53 protein (International Journal of Cancer, 55, 453-458, 1993). In addition to these, it has been reported that it is inhibited IGF-IR expression by a Wilms' tumor suppressor gene product WT1 (Journal of Biological Chemistry, 269, 12577-12582, 1994, 140, 4713-4724, 1999), and it is inhibited a mammary-derived growth inhibitor (MDGI) expression by IGF-I (International Journal of Oncology, 13, 577-582, 1998).
Relationship between life style such as energy intake and oncogenesis has been drawing attention from old times, and it is now partially revealed based on various animal tests that energy intake and expression of IGF, further oncogenesis, have a close relationship. In rats transplanted with prostate cancer, proliferation of the cancer is inhibited and apoptosis is induced when energy intake is restricted. This effect is correlated with the reduction of IGF-I concentration in blood (Journal of the National Cancer Institute, 91, 512-523, 1999). Similar result has been reported on breast cancer-transplanted mouse, and since the proliferation inhibitory function becomes un-observable by the administration of IGF-I, it is suggested that IGF-I is taking a main role in the proliferation inhibition of cancer by the restriction of energy intake (Cancer Research, 57, 4667-4672, 1997).
Relevancy of IGF to cancer has been examined also by clinical and epidemiological studies. It has been reported that IGF-I concentration in blood plasma and serum is high in breast cancer patients in comparison with healthy persons (European Journal of Cancer, 29A, 492-497, 1993, Tumori, 80, 212-215, 1994), and the amount of IGF-IR in breast cancer tissue is 10 times-higher than that in normal tissue (Cancer Research, 53, 3736-3740, 1993). Also, since the loss of heterozygosity in IGF-IIR gene was found in about 30% of breast cancer patients, it was suggested that the IGF-IIR gene has a function as a cancer suppressor gene (Breast Cancer Research & Treatment, 47, 269-281, 1998). It has been reported that concentrations of IGF-II, IGFBP-2 and IGFBP-3 in sera are high in colon cancer patients in comparison with those of healthy persons (International Journal of Cancer, 57, 491-497, 1994). In addition, it has been shown that serum concentrations of IGF-II and IGFBP-2 are high in patients of colon adenoma known to progress to be colon cancer, but these concentrations are reduced by the excision of adenoma (Journal of Clinical Endocrinology & Metabolism, 85, 3402-3408, 2000). Over-expression of IGF-II in gastric cancer tissue has been reported (European Journal of Cancer, 37, 2257-2263, 2001). It has been reported that, in patients of endometrial cancer after menopause, serum IGF-I concentration is high and the IGFBP-1 concentration is low in comparison with those of healthy persons. On the other hand, a difference was not found regarding the IGFBP-3 concentration (Endocrine Journal, 44, 419-424, 1997). It has been reported that, in patients of prostate cancer, IGF-I and IGFBP-2 concentrations are high and IGFBP-3 concentration is low in sera (British Journal of Cancer, 76, 1115-1118, 1997, Urology, 54, 603-606, 1999, Journal of Clinical Endocrinology & Metabolism, 76, 1031-1035, 1993, Journal of Clinical Endocrinology & Metabolism, 77, 299-233, 1993), and production of IGF-II, IGFBP-2, IGFBP-4 and IGFBP-5 is accelerated and production of IGFBP-3 is inhibited in the cancer tissue (Journal of Clinical Endocrinology & Metabolism, 81, 3774-3782, 1996, Journal of Clinical Endocrinology & Metabolism, 81, 411-420, 1996, Journal of Clinical Endocrinology & Metabolism, 81, 3783-3792, 1996). Similar changes in the expression of IGF-I and IGFBP have been observed also in sera and cancer tissues of ovarian cancer patients (Journal of Clinical Endocrinology & Metabolism, 78, 271-276, 1994, Journal of Clinical Endocrinology & Metabolism, 82, 2308-2313, 1997, British Journal of Cancer, 73, 1069-1073, 1996).
It has been revealed based on several epidemiological studies that there is a relevancy between the IGF and IGFBP, and the morbidity risk of cancer. It has been reported that highness of morbidity risk and highness of IGF-I concentration in blood and lowness of IGFBP-3 concentration in blood show a positive correlation in solid cancers such as breast cancer, colon cancer, rectum cancer, prostate cancer and lung cancer, that highness of morbidity risk and lowness of IGFBP-3 concentration show a positive correlation in infantile leukemia, and that highness of morbidity risk and highness of the concentration ratio of IGF-I and IGFBP-3 (IGF-I/IGFBP-3) show a positive correlation in breast cancer (Lancet, 351, 1393-1396, 1998, Science, 279, 563-566, 1998, Journal of the National Cancer Institute, 91, 620-625, 1999, Journal of the National Cancer Institute, 91, 151-156, 1999, International Journal of Cancer, 62, 266-270, 1995, Epidemiology 9, 570-573, 1998, Breast Cancer Research & Treatment, 47, 111-120, 1998, International Journal of Cancer, 83, 15-17, 1999, International Journal of Cancer, 80, 494-496, 1999, British Journal of Cancer, 76, 1115-1118, 1997).
There are reports also on the relevancy of IGF to prognosis of cancer. In the case of breast cancer, it has been reported that expression of IGF-IR is increased in an estrogen receptor- or progesterone receptor-positive tissue (Cancer Research, 52, 1036-1039, 1992). Also, there are cases reporting that the prognosis is getting poor by the expression of IGF-IR (Cancer Research, 57, 3079-3083, 1997, Cancer, 58, 1159-1164, 1998). It has also been reported that expression of estrogen receptor and expression of IGFBP-3 in the tissue have an inverse correlation (Cancer Research, 52, 5100-5103, 1992, Journal of Cellular Biochemistry, 52, 196-205, 1993).
Also, abnormal promotion of IGF function has been found in diabetic complications such as diabetic retinopathy and diabetic nephropathy (Science, 276, 1706-1709, 1997, American Journal of Physiology, 274, F1045-F1053, 1998).
In addition, it has been reported that local expression of IGF-I is observed in rheumatic synovial membrane and also that IGF-I is concerned in the formation of morbid state of reumatoid arthritis (Arthritis & Rheumatism, 32, 66-71, 1989, Journal of Rheumatology, 22, 275-281, 1995, Journal of Clinical Endocrinology & Metabolism, 81, 150-155, 1996, Arthritis & Rheumatism, 39, 1556-1565, 1996).
As described above, the IGF family proteins (IGF, IGF-R, IGFBP) including IGF-I and IGF-II are taking important roles in the oncogenesis and proliferation of cancer and also in diabetic complications and rheumatic arthritis. These facts suggest a possibility of effecting diagnosis, prevention and treatment of cancers, diabetic complications, rheumtoid arthritis and the like using IGF family proteins as the target.
Actually, antitumor effects by inhibiting IGF functions have been reported (Biochimica et Biophysica Acta, 1332, F105-F126, 1997), for example that tumorigenicity and metastacity of high metastatic human breast cancer cells in mice are reduced and prolongation of survival period is recognized by expressing antisense RNA for IGF-IR (Cancer Gene Therapy, 7, 384-395, 2000), and a report that proliferation of human rhabdomyosarcoma cell and human breast cancer cell transplanted into mice is inhibited by an anti-IGF-IR antibody (Cancer Research, 54, 5531-5534, 1994, Journal of Clinical Investigation, 84, 1418-1423, 1989, Breast Cancer Research & Treatment, 22, 101-106, 1992). On the other hand, it has been shown that the anti-IGF-IR antibody inhibits engraftment of a human breast cancer cell showing estrogen-independent growth transplanted into mice, but dose not inhibit engraftment of a human breast cancer cell showing estrogen-dependent growth or proliferation of the engrafted human breast cancer cell, indicating that sufficient antitumor effect cannot be obtained by the inhibition of IGF-IR function alone (Breast Cancer Research & Treatment, 22, 101-106, 1992).
Several antibodies are already known as the antibody to IGF (hereinafter referred to as anti-hIGF antibody). As a typical antibody to human IGF-I (hereinafter referred to as anti-hIGF-I antibody), sm1.2 has been reported (Proceedings of the National Academy of Sciences of the United States of America, Vol. 81 (1984) 2389-92. It has been revealed that sm1.2 has about 5% cross reactivity with hIGF-II, can detect 100 ng of hIGF-I by western blotting at a concentration of 1 to 2 μg/ml, and inhibits proliferation of a mouse fibroblast cell line BALB/c3T3 by 20 ng/ml of hIGF-I at a concentration of 10 to 30 μg/ml (Proceedings of the National Academy of Sciences of the United Slates of America, Vol. 81 (1984) 2389-92, Journal of Clinical Investigation, Vol. 99 (1997) 296 1-70.
Val59-SmC121 is another anti-hIGF-I antibody, and it has been reported that said antibody does not react with human insulin and hIGF-II, recognizes a peptide containing 10th to 12th position Leu-Val-Asp of hIGF-I, and shows 1 ng/ml of hIGF-I detection sensitivity by a radioimmunoassay using 125I-hIGF-I (Journal of endocrinology, 125, 327-335, 1990).
It has been reported that an anti-hIGF-I antibody 41/81 has 3% cross reactivity with hIGF-II, and shows 1 ng/ml of hIGF-I detection sensitivity by a radioimmunoassay using 125I-hIGF-I (FEBS Letters, 149, 109-112, 1982).
It has been reported that an anti-hIGF-I antibody 35117 has about 0.5% cross reactivity with hIGF-II, can detect 1 μg of hIGF-I by western blotting at a concentration of 1 μg/ml, entirely inhibits proliferation of a mouse fibroblast cell line BALB/c3T3 by hIGF-I at a concentration of 12 μg/ml or more, inhibits auto-phosphorylation of hIGF-IR by 1 μg/ml of hIGF-I at a concentration of 30 μg/ml, and shows 0.1 nM of hIGF-I detection sensitivity by a radioimmunoassay using 125I-hIGF-I (Hybridoma, 16, 513-518, 1997).
It has been reported that an anti-hIGF-I antibody BPL-M23 shows a binding activity of 10.5×109 M−1 for hIGF-I, on the other hand, shows respective cross reactivity of 0.8% and 0.0001% with hIGF-II and human insulin, shows reactivity with the IGF of goat, pig, sheep, cattle and rabbit but does not react with the IGF of rat and mouse, and inhibits fat formation for rat adipocyte by hIGF-I (Journal of Molecular Endocrinology, 2, 201-206, 1989).
It has been reported that anti-hIGF-I antibodies 7A1, 1B3, 4C1 and 5A7 recognize different epitopes of the C and D domains of hIGF-I, and show respective cross reactivity of 6.6%, 0.83%, 12% and 1.2% with hIGF-II (Hybridoma, 12, 737-744, 1993).
It has been reported that 3D1/2/1 reacts with the IGF-I of human and guinea pig but does not react with the IGF-I of rabbit, rat and mouse, and shows a cross reactivity of 7% with hIGF-II (Journal of Clinical of Metabolism, 54, 474-476, 1982).
As a typical antibody to human IGF-II (hereinafter referred to as anti-hIGF-II antibody), an S1F2 has been reported. It has been revealed that the S1F2 has a cross reactivity of about 10% with hIGF-I, can detect 10 to 100 ng of hIGF-II by western blotting at a concentration of 1 μg/ml, and inhibits the DNA synthesis promoting function of human fibroblast by 100 ng/ml of hIGF-II at a concentration of 100 μg/ml (Diabetes Research and Clinical Practice, 7, S21-S27, 1989, Endocrinology, 124, 870-877, 1989).
It has been reported that anti-hIGF-II antibodies 2H11, 2B11, ID5 and ID9 react with hIGF-II but do not react with hIGF-I, and can determine 1 ng/ml of hIGF-II by competitive enzyme immunoassay (hereinafter referred to as ELISA) (Japanese published unexamined application No. 252987/93).
In addition, it is known that when an antibody of a non-human animal, for example a mouse antibody, is administered to human, the administered mouse antibody is recognized as a foreign body, which induces in the human body a human antibody to the mouse antibody (human anti-mouse antibody: hereinafter referred to as HAMA). It is known that the HAMA reacting with the administered mouse antibody to induce side effects (Journal of Clinical Oncology, 2, 881-891, 1984; Blood, 65, 1349-1363, 1985; Journal of the National Cancer Institute, 80, 932-936, 1988; Proceedings of the National Academy of Sciences of the United States of America, 82, 1242-1246, 1985), promotes disappearance of the administered mouse antibody from the body (Journal of Nuclear Medicine, 26, 1011-1023, 1985; Blood, 65, 1349-1363, 1985; Journal of the National Cancer Institute, 80, 937-942, 1988) and reduces therapeutic effect of the mouse antibody (Journal of Immunology, 135, 1530-1535, 1985; Cancer Research 46, 6489-6493, 1986).
In order to solve these problems, attempts have been made to convert antibodies of non-human animals into humanized antibodies such as human chimeric antibodies and human complementarity determining region (hereinafter referred to as CDR)-grafted antibodies by using gene recombination techniques. The human chimeric antibody is an antibody wherein variable region (hereinafter referred to as V region) of the antibody is an antibody of a non-human animal and constant region (hereinafter referred to as C region) is a human antibody (Proceedings of the National Academy of Sciences of the United States of America, 81, 6851-6855, 1984), and the human CDR-grafted antibody is an antibody wherein amino acid sequence of CDR in the V region of an antibody of a non-human animal is grafted to an appropriate position of a human antibody (Nature, 321, 522-525, 1986). In comparison with antibodies of non-human animals such as mouse antibody, these humanized antibodies are more advantageous in clinical applications to human. For example, regarding immunogenicity and stability in blood, it has been reported that blood half-life of a human chimeric antibody was extended about 6 times in comparison with a mouse antibody when administered to human (Proceeding of the National Academy of Sciences of the United States of America, 86, 4220-4224, 1989). As to a human CDR-grafted antibody, it has been reported that its immunogenicity was reduced and blood half-life was extended in comparison with a mouse antibody in a study using a monkey (Cancer Research, 56, 1118-1125, 1996; Immunology, 85, 668-674, 1995). Thus, it is expected that humanized antibodies have less side effects in comparison with antibodies of non-human animals, and their-therapeutic effects are maintained for a long period of time. Further, humanized antibodies are prepared by using gene recombination techniques, and they can be prepared as various forms of molecules. For example, when a γ-1 subclass is used as the heavy chain (hereinafter referred to as H chain) C region of a human antibody, a humanized antibody which is stable in blood and has high effector activities such as antibody-dependent cellular cytotoxicity and the like can be prepared (Cancer Research, 56, 1118-1125, 1996). A humanized antibody having high effector activity is markedly useful when destruction of targets such as cancer is desired. On the other hand, in the case that merely a target-neutralizing function alone is required, or in the case that there is a possibility of causing a side effect due to destruction of a target by an effector activity, a γ4 subclass is suitably used as the H chain C region of a human antibody, because γ4 subclass generally has low effector activity (Journal of Experimental Medicine, 166, 1351-1361, 1987; Journal of Experimental Medicine, 168, 127-142, 1988), and side effects can be avoided, and further extension of blood half-life in comparison with a mouse antibody can be expected (Immunology, 85, 668-674, 1995). In addition, with the recent advances in protein engineering and genetic engineering, it became possible to prepare antibody fragments having more smaller molecular weight such as Fab, Fab′, F(ab′)2, scFv (Science, 242, 423-426, 1988), dsFv (Molecular Immunology, 32, 249-258, 1995) and CDR-containing peptide (Journal of Biological Chemistry, 271, 2966-2971, 1996) from antibodies including humanized antibodies. Since these antibody fragments have smaller molecular weight in comparison with whole antibody molecules, they have superior transferring property to target tissues (Cancer Research, 52, 3402-3408, 1992).
Based on the above, the IGF family proteins which take important roles in the oncogenesis and proliferation of cancer and also in diabetic complications and rheumatoid arthritis are controlling these diseases through complicated entanglement of growth factors including insulin, IGF-I and IGF-II, receptors including insulin receptor, IGF-IR and IGF-IIR and IGFBP. Accordingly, it is difficult to suppress these diseases completely by inhibiting a part of these interactions. Though there are many reports on antibodies which recognize IGF-I and/or IGF-II considered to be useful as medicament, there are no reports on antibodies which can simultaneously inhibit functions of IGF-I and IGF-II by strongly binding to IGF-I and IGF-II.
In addition, as antibodies to be used for the clinical application to human, humanized antibodies are desirable than antibodies of a non-human animal such as mouse antibody. However, there are no reports on the preparation of recombinant antibodies such as humanized antibody as an anti-hIGF antibody, and also on antibody fragments thereof.